document contribution policy for adding software to EESSI

docs/software_layer/adding_software.md

@@ -9,6 +9,10 @@ To add software to EESSI, you should go through the semi-automatic software inst
 * 3) Instructing the [bot :robot:](../bot.md) to deploy the built software for ingestion into the EESSI repository;
 * 4) Merging the pull request once CI indicates that the software has been ingested. :white_check_mark:
 
+!!! warning
+
+    Make sure you are also aware of our [contribution policy](contribution_policy.md) when adding software to EESSI.
+
 ### Preparation
 
 Before you can make a pull request to the [software-layer](https://github.com/EESSI/software-layer),

docs/software_layer/contribution_policy.md

@@ -0,0 +1,80 @@
+# Contribution policy
+
+When [openining a pull request to add software to EESSI](adding_software.md), the following requirements must
+be taken into account.
+
+!!! note
+
+    These requirements are subject to change, please check back regularly.
+
+## Open source software
+
+Only **open source software** can be added to the EESSI repository.
+
+Make sure that you are aware of software license, and that redistribution is allowed.
+
+For more information about a specific license, see the [SPDX license list](https://spdx.org/licenses/).
+
+!!! note
+
+    We intend to automatically verify that this requirement is met,
+    by requiring that the [SPDX license identifier](https://spdx.dev/ids/) is provided for all software.
+
+## Built by the bot
+
+All software included in the EESSI repository *must* be built autonomously by [our bot :robot:](../bot.md),
+see also the [semi-automatic software installation procedure](adding_software.md).
+
+## Supported by EasyBuild
+
+Currently, we require that all software being added to EESSI is supported by the *EasyBuild release* being used
+to perform the installation.
+
+That is, the easyconfig files used for the installation *must be included in the EasyBuild release*.
+
+We do allow the use of [`--from-pr`](https://docs.easybuild.io/integration-with-github/#github_from_pr) and
+[`--include-easyblocks-from-pr`](https://docs.easybuild.io/integration-with-github/#github_include_easyblocks_from_pr)
+to pull in changes required to make the installation work correctly in the EESSI build environment,
+but only if that is strictly required.
+
+!!! note
+
+    This restriction may be relaxed later to also allow adding software that is not supported yet in the latest
+    EasyBuild release, or to allow for installing software with other tools.
+
+## Supported compiler toolchains
+
+A [compiler toolchain](https://docs.easybuild.io/terminology/#toolchains) that is still supported by the latest
+EasyBuild must be used for building the software.
+
+More information on deprecated toolchains in EasyBuild is available
+[here](https://docs.easybuild.io/deprecated-easyconfigs/#deprecated_easyconfigs_toolchains).
+
+## Supported CPU targets
+
+The software *should* work on all [CPU targets supported by EESSI](cpu_targets.md).
+
+Exceptions to this requirement are allowed if technical problems that can not be resolved with reasonable effort
+prevent the installation of the software for specific CPU targets.
+
+## Software versions & toolchains
+
+Recent software versions and toolchains *should* be preferred,
+although the installation of older versions of use of older toolchains is allowed if sufficiently motivated.
+
+## Testing
+
+We should be able to test the software installations via the [EESSI test suite](https://github.com/EESSI/test-suite)
+being developed.
+
+Ideally one or more tests are available that verify that the software is functionally correct,
+and performs well.
+
+It should be possible to run a minimal *smoke test*, for example using EasyBuild's `--sanity-check-only` feature.
+
+!!! note
+
+    The [EESSI test suite](https://github.com/EESSI/test-suite) is still in active development,
+    and currently only has a minimal set of tests available.
+
+    When the test suite is more mature, this requirement will be enforced more strictly.

mkdocs.yml

@@ -26,6 +26,7 @@ nav:
     - software_layer/cpu_targets.md
     - software_layer/build_nodes.md
     - software_layer/adding_software.md
+    - software_layer/contribution_policy.md
   - Build-test-deploy bot: bot.md
   - Pilot repository: pilot.md
   - Getting access to EESSI: